DENTAL HARD TISSUE DESTRUCTION 145 



to both inorganic and organic elements involved in the fluid-solid 

 equilibrium of the mouth (Sognnaes, 1957i»). 



From a mechanical point of view it is known that self-cleansing 

 surfaces of enamel can tolerate a certain degree of grinding and 

 polishing. In one clinical report Rushton ( 1957 ) has indicated suc- 

 cessful practical results with rather extensive mechanical "remodel- 

 ing" of the enamel for cosmetic purposes. 



Thus, there are at least preliminary observations to suggest that 

 the original intact enamel surface may no longer be considered in- 

 violate. If it is partially destroyed — within a certain degree and 

 depth — there appears to exist a limited capacity for reconstitution 

 to clinically normal quality and appearance. This chemical repair 

 appears to operate whether the original enamel surface has been 

 destroyed by chemical action (as in our own experiments), by 

 pathological demineralization (as in incipient caries), or by me- 

 chanical abrasion (as in cosmetic "remodeling" of malshaped or 

 malposed teeth). 



Concluding Comparisons and Summary 



Having made references to various types of hard tissue destruction 

 over and beyond dental erosion — the principal theme of this pre- 

 sentation — it seems appropriate in a few concluding paragraphs to 

 present a brief summarizing comparison between the various types 

 of dento-alveolar destruction processes from the point of view of 

 microradiographic and histopathological characteristics. This com- 

 parison is presented in parallel fashion in Fig. 30A to G (micro- 

 radiographs of ground sections ) and Fig. 30a to f ( photomicrographs 

 of decalcified sections), and diagrammatically summarized in Fig. 

 31. 



Fig. 30. Microradiographs of ground sections (left row, A to G) and photo- 

 micrographs of decalcified sections (right row, a to f) from dento-alveolar 

 structures subjected to various mechanisms of hard tissue destruction: A, a, 

 enamel caries; B, b, dentin caries; C, c, dentinal erosion; D, dentinal abrasion; 

 E, d, alveolar bone resorption; F, e, dentin and enamel (e) resorption; G, f, ce- 

 mentum and dentin boring canals produced by postmortem saprophytes. For 

 comparative comments and conclusions see text. 



